From d807ed1c55fb1b2dcfb2bc49385e227f6bee7669 Mon Sep 17 00:00:00 2001 From: Brian Starkey Date: Thu, 13 Oct 2016 10:47:08 +0100 Subject: drm: atomic: Clarify documentation around drm_atomic_crtc_needs_modeset Add some additional comments to more explicitly describe the meaning and usage of the three CRTC modeset detection booleans: mode_changed, connectors_changed and active_changed. Suggested-by: Daniel Vetter Signed-off-by: Brian Starkey Acked-by: Alex Deucher Signed-off-by: Daniel Vetter Link: http://patchwork.freedesktop.org/patch/msgid/1476352028-16701-1-git-send-email-brian.starkey@arm.com --- include/drm/drm_atomic.h | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) (limited to 'include/drm/drm_atomic.h') diff --git a/include/drm/drm_atomic.h b/include/drm/drm_atomic.h index 9701f2dfb784..c52f99415c55 100644 --- a/include/drm/drm_atomic.h +++ b/include/drm/drm_atomic.h @@ -365,8 +365,17 @@ int __must_check drm_atomic_nonblocking_commit(struct drm_atomic_state *state); * * To give drivers flexibility struct &drm_crtc_state has 3 booleans to track * whether the state CRTC changed enough to need a full modeset cycle: - * connectors_changed, mode_changed and active_change. This helper simply + * connectors_changed, mode_changed and active_changed. This helper simply * combines these three to compute the overall need for a modeset for @state. + * + * The atomic helper code sets these booleans, but drivers can and should + * change them appropriately to accurately represent whether a modeset is + * really needed. In general, drivers should avoid full modesets whenever + * possible. + * + * For example if the CRTC mode has changed, and the hardware is able to enact + * the requested mode change without going through a full modeset, the driver + * should clear mode_changed during its ->atomic_check. */ static inline bool drm_atomic_crtc_needs_modeset(struct drm_crtc_state *state) -- cgit v1.2.3-70-g09d2